Links for IEC61850

Links for IEC61850

1. http://www.61850.com/ This link is useful if you want to check the validation of the SCD or ICD or CID files.
2. http://www.tissues.iec61850.com/default.mspx
3. http://en.wikipedia.org/wiki/IEC_61850 This is the general wiki. But has few very good presentation on IEC61850.
4. http://siemens.siprotec.de/download_neu/applications/IEC61850/IEC61850_message_status.pdf
   Interrogation of the IEC61850 message status
   Why is it not possible to detect a failure with convention wiring via binary input?
   A loss of signal can also occur on protocol based communication links
   Why does IEC61850 detect an interruption of the transmission path?
   How does one obtain the message status?
5. http://siemens.siprotec.de/download_neu/applications/IEC61850/design01/Network%20Sketch%20Design%2001.pdf This link describes the network overview in standard IEC61850 station.
6. http://siemens.siprotec.de/download_neu/applications/IEC61850/design01/Description%20Design%2001.pdf This link explains the limitation on the number of devices to be connected to the network switch, how many rings are possible in a subnet and many other configuration checklist.
   

Concepts to know in Network before you work with IEC-61850 protocol

Concepts to know in Network before you work with IEC-61850 protocol:

1. Different IP address - Class B, Class A, ...
2. Different MAC address -
3. What is multicast mac address?
4. What is RSTP ? Rapid Spanning Tree Protocol.
5. Which protocol is used for Client-Server Communication?
6. What is subnet?How is it decided ?
7. What is multimode FO cable vs Single mode FO cable?
8. Which type of cables are to be used for SIE, SEL and GE devices?
9. XML, HTML, SCL ...
10. Ethernet TCP/IP
11. OSI
12. Network Switches
13. How they perform?
14. Client - Server communication

Will post the brief description later on.

Advantages of using IEC61850 Protocol

Advantages of using IEC61850 Protocol

1. Reduced Hardwiring
2. Improved Performance
3. Improved capability
4. Customized Solutions
5. Flexibility of the various protection/control schemes
6. Improved supervision
7. Trouble shooting much easier
8. Reduced man-power requirement
9. Reduced chances of error
10. Faster completion of project
11. Reduced space requirement
12. Improved functionality
13. Easy to carry out changes/modifications
14. No aging issues

AutoReclose Function in Protection Relays

Auto Reclose Function:

Technically, whenever any transient faults causing the trip of the circuit breaker, mainly for Over head lines occur, most of utilities prefer to reclose the breaker or they try to reclose for number of times, before coming to the conclusion that the fault is permanent.



You must know which kind of faults you need to consider for transient faults. Not all faults are transient. Ph-Gd, O/C or Multi-phase faults generally account for Transient faults. These AR initiation can be other source too. Energized by user-defined precondition to start AR. As per Siemens Relays, Non-directional faults/Directional/Other/via BI is possible. But it is important that fault occurs. Unless relay sees a fault and breaker trips due to that fault, AR sequence will not start.

• AR and Synch Check goes hand in hand. So when you configure any protection, enable 79 (for auto-reclose)and 25(for synch check).


• So, to first know what is AR and then what is synch check to understand AR sequence.


• it is also important to know Power System Data, V, f, VT connection, Vsynch connection, etc.


• Always set the AutoReclose function.


• Use Inbuilt function for checking how auto reclose works by initiating Overcurrent fault.


• Check then how the sequence is initiated.

Source:

1. Siemens Manual for Line Relay 7SA522/

http://siemens.siprotec.de/download_neu/index_e.htm

Important things to know about REF ( Restricted Earth Fault Relays)

Why REF required?????
REF protection applied on transformer in order to detect ground faults on a given winding more sensitively than overall differential protection able to do.

On which principle they based ?????
The principle of comparison of measured variables by comparing the residual current of the phase CT of the given winding with the current associated with ground star point.

Why residual current occur????? or why CT saturated???
Saturation Saturation is the sudden variation of material permeability from high value to low value at the point known as the saturation bend.

In case of saturation induction then increases only slowly and Ie ( excitation current ) deforms to form peak.

Why stabilizing resistor inserted in the differential path for REF relay ???
If any CT ( phase CT or neutral CT ) get saturation (due to DC component of current during trafo energization (Inrush current)) .
So CT 's high magnetizing inductance breaks down to low value determined by permeability of air.
Differential current or residual current caused by CT saturation does not flow completely through differential path (due to high Impedance in path) but flows through low magnetizing inductance of saturated CT.
Hence insertion of resistance has a restraining effect.
Voltage across stabilizing resistance at Max. through fault = Max. through fault current ( CT resistance + 2 * Cable resistance )

BTW we are never allow to saturate our CT's by selecting proper knee point voltage.